This invention relates to a thermally stable diamond abrasive compact body.
Diamond abrasive compacts are well known in the art and consist essentially of a mass of diamond abrasive particles present in an amount of at least 70 percent, preferably 80 to 90 percent, by volume of the compact bonded into a hard conglomerate. Compacts are polycrystalline masses and can replace single large crystals in many applications
Diamond compacts will typically contain a second phase uniformly distributed through the diamond mass. The second phase may contain a dominant amount of a catalyst/solvent for diamond synthesis such as cobalt, nickel or iron. Diamond compacts having second phases of this nature will generally not have thermal stability above 700.degree. C.
Diamond abrasive compacts may be used alone or as composite compacts in which event they are backed with a cemented carbide substrate. Composite diamond abrasive compacts wherein the second phase contains a diamond catalyst/solvent are widely used in industry.
Examples of composite diamond abrasive compacts are described in U.S. Pat. No. 3,745,623 and British Patent Specification No. 1,489,130.
Diamond abrasive compacts of the type described above are thermally sensitive above a temperature of about 700.degree. C. There are, however, described in the literature and in commercial use several diamond abrasive compacts which are thermally stable above 700.degree. C. For example, U.S. Pat. No. 4,224,380 describes a thermally stable diamond compact which comprises self-bonded diamond particles comprising between about 70% and 95% by volume of the product, a metallic phase infiltrated substantially uniformly throughout the product, the phase comprising between about 0.05% and 3% by volume of the product and a network of interconnected, empty pores dispersed throughout the product and defined by the particles and the metallic phase, the pores comprising between 5% and 30% by volume of the product.
U.S. Pat. No. 4,534,773 describes a thermally stable diamond abrasive compact which comprises a mass of diamond particles present in an amount of 80 to 90% by volume of the body and a second phase present in an amount of 10 to 20% by volume of the body, the mass of diamond particles containing substantial diamond-to-diamond bonding to form a coherent, skeletal mass and the second phase containing nickel and silicon, the nickel being in the form of nickel and/or nickel silicide and the silicon being in the form of silicon, silicon carbide and/or nickel silicide.
British Patent Publication No. 2158086 describes a thermally stable diamond abrasive compact similar to that described in U.S. Pat. No. 4,534,773 save that the second phase consists essentially of silicon in the form of silicon carbide and/or silicon.
Difficulty has been experienced in the past in producing a composite diamond abrasive compact or carbide supported wire-drawing die wherein the diamond compact is a thermally stable one of the type described above. To the best of the Applicant's knowledge, no such products are as yet commercially available.